Rockie's Android Porting Guide（4）——Add SD card to your system

Rockie Cheng

Andorid use vold to manage SD card and it is easy to use.
But I meet many troubles and finally find that the real problem is in the Linux Kernel.
Thanks to the Android Mail List.

Part I (kernel)

(1)make sure thus kernel configuration in MMC driver

CONFIG_MMC=y
# CONFIG_MMC_DEBUG is not set
CONFIG_MMC_UNSAFE_RESUME=y
# CONFIG_MMC_EMBEDDED_SDIO is not set
CONFIG_MMC_PARANOID_SD_INIT=y

#
# MMC/SD Card Drivers
#
CONFIG_MMC_BLOCK=y
CONFIG_MMC_BLOCK_BOUNCE=y
# CONFIG_MMC_BLOCK_PARANOID_RESUME is not set
# CONFIG_SDIO_UART is not set
# CONFIG_MMC_TEST is not set

#
# MMC/SD Host Controller Drivers
#
CONFIG_MMC_SDHCI=y

(2)Disable this option
General Setup -> Create deprecated sysfs layout for older userspace tools

Before I did this,vold showed a lot of trouble.
And ,my media_path is not right
media_path /devices/platform/s3c-sdhci.0/mmc_host:mmc0<--my path before turn off that option

media_path /devices/platform/s3c-sdhci.0/mmc_host/mmc0 <--this is the right one

Vold may be unhappy to accept my old path,and it didn't work.

D/vold ( 42): Accepted connection from framework
D/vold ( 42): dispatch_cmd(send_ums_status):
D/vold ( 42): dispatch_cmd(mount_volume:/sdcard):
E/vold ( 42): Cannot start volume '/sdcard' (volume is not bound)
D/MountListener( 59): handleEvent volume_nomedia:/sdcard
D/MountListener( 59): handleEvent ums_disabled
D/MountListener( 59): handleEvent ums_disconnected

(3) rebuild your linux kernel

PART II(android system)

(1) creat a vold.conf in build/target/board/idea6410

## vold configuration file for idea6410

volume_sdcard {
## This is the direct uevent device path to the SD slot on the device
media_path /devices/platform/s3c-sdhci.0/mmc_host/mmc0

media_type mmc
mount_point /sdcard
ums_path /devices/platform/usb_mass_storage/lun0
}

(2)add those below to AndroidBoard.mk

include $(CLEAR_VARS)
LOCAL_MODULE_CLASS := ETC
LOCAL_MODULE := vold.conf
LOCAL_SRC_FILES := $(LOCAL_MODULE)
include $(BUILD_PREBUILT)

(3)rebuild the system and check init.rc

service vold /system/bin/vold
socket vold stream 0660 root mount

(4)enjoy

D/vold ( 42): Accepted connection from framework
D/vold ( 42): dispatch_cmd(send_ums_status):
D/vold ( 42): dispatch_cmd(mount_volume:/sdcard):
I/vold ( 42): Evaluating dev '/devices/platform/s3c-sdhci.0/mmc_host/mmc0/mmc0:e624/block/mmcblk0' for mountable filesystems for '/sdcard'
D/MountListener( 61): handleEvent volume_unmounted:/sdcard
D/MountListener( 61): handleEvent ums_disabled
D/MountListener( 61): handleEvent ums_disconnected
D/MountListener( 61): handleEvent volume_checking:/sdcard

Rockie Cheng

阿虚

Rockie's Android Porting Guide（4）——Add SD card to your system

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